The present invention relates to a cracking catalyst additive and process for preparing the cracking catalyst additive. Particularly, this invention relates to a fluid cracking catalyst additive (xe2x80x9cFCC additivexe2x80x9d) for promoting the combustion of carbon monoxide to carbon dioxide in the regeneration of a fluid cracking catalyst.
Catalyst manufacturers are continuously seeking catalysts, additives, and processes to improve the properties of catalysts and additives to lower the cost of producing catalysts and additives. Catalyst and additive producers, typically, search for materials, equipment, or processes that decrease the cost of raw materials or utilities, or increase the efficiency of the catalyst process with increased feed through-put, lower equipment maintenance, or improved utilization of raw materials. All these factors contribute to the manufacturing costs of catalysts and additives.
The use of transition metals in specific fluid cracking catalyst formulations can improve the selectivity of a given fluid cracking catalyst unit, using a specific gas oil feed, but results in undesired concentrations of coke and yields of light gas. The undesirable loss of gasoline yield and increases in coke and light gases with transition metal formulations diminishes the value of the enhanced production of desirable products such as olefins.
Rare earth complex oxide combustion catalysts have been proposed in U.S. Pat. No. 5,242,881 to Tang et al. In this patent, perovskite-type rare earth complex oxide active components are carried on a support using mullite as the main phase. In the prior art section of the Tang et al. patent, the use of perovskite-type rare earth complex oxides as active components of a catalyst have attracted wide attention due to their catalytic oxidizing function for carbon monoxide and hydrocarbons. The Tang et al. patent further states that catalysts using perovskite-type complex oxides as the active components are generally carried on xcex3-AL2O3. These supports are noted to inevitably react chemically with the complex oxide. As a result, aluminum-containing perovskite or aluminum-containing spinel with non-catalytic activity is formed, causing part of the active components to be damaged, so that the activity of the catalysts dropped universally. Attempts have been made to solve the problem by precoating or using the active components as catalysts alone without support. The Tang et al. patent solves these problems by using a support with mullite as a main phase for a perovskite-type active component having the following general formula:
{[A1xe2x88x92xAxe2x80x2x]1xe2x88x92yxe2x96xa1y}{B1xe2x88x92zBxe2x80x2z]2xe2x88x92wxe2x96xa1w}O3xe2x88x92xcex4
wherein A represents a rare earth metal element, preferably La, Ce or mixed rare earths and most preferably, La or Ce; Axe2x80x2 represents an alkaline earth metal element, preferably Ca, Sr or Ba and most preferably Ca or Sr, xe2x96xa1 represents the vacancy in the structure; B and Bxe2x80x2 represent the transition metal elements, preferably Ti, Cr, Co, Mn, Cu, Fe or Ni, and most preferably Ti, Cr, Co or Mn; 0xe2x89xa6xxe2x89xa60.9; 0xe2x89xa6yxe2x89xa60.2; 0xe2x89xa6zxe2x89xa60.9; 0xe2x89xa6wxe2x89xa60.05; 0xe2x89xa6xcex4xe2x89xa60.8. And a support with mullite as the main phase, wherein the said active components are carried directly on the said support.
U.S. Pat. No. 3,897,367 to Lauder discloses metal oxide catalytic compounds which are also of the perovskite-type ABO3 structure wherein 1-20% of the B site cations are ruthenium or platinum. The composition of the Lauder patent is an improvement over rare earth cobaltite catalytic compositions.
There exists a continuing need for improved catalyst which promote the combustion of carbon monoxide to carbon dioxide under conditions prevailing in a fluid catalytic cracking (FCC) regenerator.
The invention is a catalyst composition. The composition includes at least one Group VIII transition metal with at least one Group IB transition metal on a support.
The invention is also a process for producing a combustion promotor catalyst of carbon monoxide to carbon dioxide. The process includes mixing aqueous solutions of effective concentrations of at least one Group VIII transition metal and at least one Group IB transition metal. Then, the mixed, aqueous solutions are injected under pressure onto a support, e.g., any type of alumina, such as alpha (xcex1) or gamma (xcex3) alumina. In an embodiment of the present invention, the mixed aqueous solutions are injected under pressure on to microspheroidal alumina powder, to impregnate the micro-spheroidal alumina powder. The impregnated microspheroidal alumina powder is then dried.